Criteria for disk susceptibility tests and quality control guidelines for the cefoperazone-sulbactam combination

Abstract

For in vitro susceptibility tests with cefoperazone and sulbactam (a I-lactamase inhibitor), 75/30-,ig disks may be used with the interpretive zone size breakpoints that are currently used for 75-,ug cefoperazone disks. For dilution tests, a 2:1 ratio of cefoperazone to sulbactam is recommended. For quality control purposes, MIC limits that are used to monitor cefoperazone tests were also applied to tests with the combination of drugs. For gram-negative control strains, zone size limits were calculated to be 1 mm smaller than those used for cefoperazone disks. To monitor the sulbactam portion of the combination, Acinetobacter calkoaceticus subsp. anitratus ATCC 43498 was selected; zones with 75/30-,ig disks were 26 to 32 mm in diameter, and broth microdilution MICs ranged from 1.0/0.5 to 8.0/4.0 ,ug/ml. With cefoperazone alone, MICs for Acinetobacter calcoaceticus subsp. anitratus were 16 to 64 ,ug/ml and zones ranged from 14 to 18 mm in diameter. For anaerobic dilution tests, only Bacteroides thetaiotaomicron ATCC 29741 is recommended for cefoperazonesulbactam; MICs ranged from 8.0/4.0 to 32/16 ,ig/ml. Although cefoperazone is relatively stable to staphylococcal 1-lactamases and to most chromosomally mediated

Genetic characterization and in�vitro activity of antimicrobial combinations of multidrug-resistant Acinetobacter�baumannii from a general hospital in China

“…In the present study, 6 drugs (iAK, SCF I, SCF II, MEM, MINO and CIP) were selected to study the in vitro activity of drug combinations against MDRAB. The lower MIC of SCFI compared with SCF II demonstrated a comparatively increased rate of in vitro activity of SCF I against MDRAB, which was incompatible with previous studies ( 33 , 34 ). This discrepancy may arise from the geographical and biological evolutional differences.…”

Prevalence of β-lactamase classes A, C, and D among clinical isolates of Pseudomonas aeruginosa from a tertiary-level hospital in Bangkok, Thailand

“…The antimicrobial susceptibility test for β-lactamase was performed using the Kirby-Bauer disk diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The antimicrobial agents used were ceftazidime (CAZ), cefepime (FEP), cefoperazone/sulbactam (SCFP), piperacillin/tazobactam (TZP), amikacin (AK), gentamicin (GM), ciprofloxacin (CFX), levofloxacin (LVX), imipenem (IPM), meropenem (MEM), and colistin (CL) (Oxoid, Basingstoke, Hampshire, England), and the results were interpreted using the CLSI 2009 criteria (Barry and Jones, 1988;Clinical and Laboratory Standards Institute, 2009).…”

Detection of resistance due to inducible beta-lactamase in Enterobacter aerogenes and Enterobacter cloacae

“…Cefoperazonesulbactam disks obtained from Pfizer Laboratories, New York, N.Y., contained 75 ,ug of cefoperazone and 30 jig of sulbactam. Interpretations (susceptible, .21 mm; resistant -15 mm) were done as described by Barry et al (1). Piperacillin-tazobactam disks with 100 and 10 ,ug, respectively, now marketed as Zosyn, were obtained from Lederle Laboratories, Pearl River, N.Y.…”